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/**
* Copyright (C) 2019-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/base/data_range.h"
#include "mongo/crypto/fle_field_schema_gen.h"
#include "mongo/crypto/symmetric_crypto.h"
#include "mongo/db/matcher/schema/encrypt_schema_gen.h"
#include "mongo/util/uuid.h"
namespace mongo {
constexpr int kAssociatedDataLength = 18;
constexpr size_t kHmacOutSize = 32;
/**
* Returns the length of the plaintext output given the ciphertext length. Only for AEAD.
*/
inline StatusWith<size_t> aeadGetMaximumPlainTextLength(size_t cipherTextLen) {
if (cipherTextLen > (crypto::aesCBCIVSize + kHmacOutSize)) {
return cipherTextLen - crypto::aesCBCIVSize - kHmacOutSize;
}
return Status(ErrorCodes::BadValue, "Invalid cipher text length");
}
/**
* Returns the length of the plaintext output given the ciphertext length. Only for FLE2 AEAD.
*/
inline StatusWith<size_t> fle2AeadGetPlainTextLength(size_t cipherTextLen) {
if (cipherTextLen > (crypto::aesCTRIVSize + kHmacOutSize)) {
return cipherTextLen - crypto::aesCTRIVSize - kHmacOutSize;
}
return Status(ErrorCodes::BadValue, "Invalid cipher text length");
}
/**
* Returns the length of the plaintext output given the ciphertext length. Only for FLE2.
*/
inline StatusWith<size_t> fle2GetPlainTextLength(size_t cipherTextLen) {
if (cipherTextLen > (crypto::aesCTRIVSize)) {
return cipherTextLen - crypto::aesCTRIVSize;
}
return Status(ErrorCodes::BadValue, "Invalid cipher text length");
}
/**
* This class is a helper for encryption. It holds a ConstDataRange over the
* plaintext to be encrypted and owns a buffer where the BinData subtype 6 is
* written out to. The encrypt function can only be called after the constructor
* to initialize the plaintext, the associated data, and the key has been called.
*/
class FLEEncryptionFrame {
public:
FLEEncryptionFrame(std::shared_ptr<SymmetricKey> key,
FleAlgorithmInt algorithm,
UUID uuid,
BSONType type,
ConstDataRange plaintext,
size_t cipherLength)
: _key(std::move(key)), _plaintext(plaintext) {
// As per the description of the encryption algorithm for FLE, the
// associated data is constructed of the following -
// associatedData[0] = the FleAlgorithmEnum
// - either a 1 or a 2 depending on whether the iv is provided.
// associatedData[1-16] = the uuid in bytes
// associatedData[17] = the bson type
if (BSONType::BinData == type) {
BinDataType subType = BSONElement::binDataType(plaintext.data(), plaintext.length());
uassert(6409402,
"Encrypting already encrypted data prohibited",
BinDataType::Encrypt != subType);
}
_data.resize(kAssociatedDataLength + cipherLength);
_data[0] = FleAlgorithmInt_serializer(algorithm);
auto uuidCDR = uuid.toCDR();
invariant(uuidCDR.length() == 16);
std::copy(
uuidCDR.data<uint8_t>(), uuidCDR.data<uint8_t>() + uuidCDR.length(), _data.begin() + 1);
_data[17] = static_cast<uint8_t>(type);
}
FLEEncryptionFrame() : _plaintext(ConstDataRange(nullptr, 0)){};
const ConstDataRange get() const& {
return ConstDataRange(_data);
}
std::shared_ptr<SymmetricKey> getKey() const {
return _key;
}
const ConstDataRange getPlaintext() const {
return _plaintext;
}
const ConstDataRange getAssociatedData() const {
return ConstDataRange(_data.data(), kAssociatedDataLength);
}
uint8_t* getCiphertextMutable() & {
invariant(_data.size() > kAssociatedDataLength);
return _data.data() + kAssociatedDataLength;
}
uint8_t* getCiphertextMutable() && = delete;
FleAlgorithmInt getFLEAlgorithmType() {
return FleAlgorithmInt_parse(IDLParserErrorContext("root"), _data[0]);
}
size_t getDataLength() const {
return _data.size() - kAssociatedDataLength;
}
private:
std::shared_ptr<SymmetricKey> _key;
std::vector<uint8_t> _data;
ConstDataRange _plaintext;
};
/**
* This is a helper class for decryption. It has a ConstDataRange over a
* vector owned by the instantiator of this class and allows
* containing the plaintext object after it has been decrypted.
*/
class FLEDecryptionFrame {
public:
FLEDecryptionFrame(ConstDataRange data) : _data(data) {
uassert(ErrorCodes::BadValue,
"Ciphertext blob too small",
_data.length() > kAssociatedDataLength);
uassert(ErrorCodes::BadValue,
"Ciphertext blob algorithm unknown",
(getFLEAlgorithmType() == FleAlgorithmInt::kDeterministic ||
getFLEAlgorithmType() == FleAlgorithmInt::kRandom));
_plaintext.resize(
uassertStatusOK(aeadGetMaximumPlainTextLength(data.length() - kAssociatedDataLength)));
}
void setKey(std::shared_ptr<SymmetricKey> key) {
_key = key;
}
std::shared_ptr<SymmetricKey> getKey() {
return _key;
}
const ConstDataRange getAssociatedData() const {
return ConstDataRange(_data.data(), kAssociatedDataLength);
}
UUID getUUID() const {
auto uuid = UUID::fromCDR(ConstDataRange(_data.data() + 1, UUID::kNumBytes));
return uuid;
}
ConstDataRange getCiphertext() const {
return ConstDataRange(_data.data() + kAssociatedDataLength, getDataLength());
}
ConstDataRange getPlaintext() const {
return ConstDataRange(_plaintext);
}
std::vector<uint8_t>& getPlaintextMutable() {
return _plaintext;
}
uint8_t getBSONType() {
return *(_data.data<uint8_t>() + 17);
}
private:
FleAlgorithmInt getFLEAlgorithmType() const {
return FleAlgorithmInt_parse(IDLParserErrorContext("root"), *_data.data<uint8_t>());
}
size_t getDataLength() const {
return _data.length() - kAssociatedDataLength;
}
std::shared_ptr<SymmetricKey> _key;
ConstDataRange _data;
std::vector<uint8_t> _plaintext;
};
} // namespace mongo
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